Preparation of magnesium seamless rings



United States Patent 3,175,287 PREPARATION OF MAGNESE UM SEAMLESS RENGS John F. Pashak, Linwood, Mich, assignor to The Dow Chemical Company, Midland, Mich, a corporation of Delaware No Drawing. Filed Sept. 13, 1961, Ser. No. 137,745 1 Claim. ((31. 29-528) This invention relates to the ring forging or ring rolling of magnesium ring blanks and is more particularly concerned With a method for the manufacture of seamless rings whereby the properties thereof are enhanced.

Generally in metal shaping operations, especially in rolling and forging magnesium base alloys, an orientation of physical properties of the metal is noted. For example, the values exhibited in respect to the tensile yield strength and to a lesser degree the tensile strength and elongation are higher in the direction of metal flow than in a direction transverse to said flow. Thus, the rolled or forged article exhibits anisotropic properties. In the case of large seamless rings, the tangential properties are greater than the axial properties when the prior art methods of preparing large seamless rings are employed.

Prior art methods for the manufacture of magnesium seamless rings included the provision of a ring blank defining an 0, upsetting the ring blank to obtain a larger ring diameter, and thereafter hot working the upset ring blank thereby to increase both diameters and to prepare a seamless ring.

The method of the present invention differs from the known art of producing large seamless rings by omitting the step of upsetting. It was unexpectedly found that when the magnesium ring blank was directly hot worked, without upsetting, the mechanical properties of the resulting ring were found to be essentially isotropic in both the tangential and axial directions.

Magnesium and magnesium base alloys, wherein the alloys contain at least 75% magnesium are suitable for use in the present invention.

Hot Working of the present invention may be accomplished in the conventional manner of ring forging or hot rolling of the ring blank. Hot working according to the present invention should increase both the internal and external diameter of the ring blank.

The following example is given for the purpose of illustration but is not to be construed as limiting the invention thereto.

EXAMPLE A magnesium base alloy having the nominal composition of 2% thorium, 0.6% manganese, the balance being magnesium was provided.

For purposes of comparison, a direct chill cast ingot having a 6.5" diameter and extruded stock having a 4" diameter were upset to 8" and 6" diameters respectively at 800 F. There was also provided an 8" diameter direct chill cast ingot and a 6 diameter extruded billet. A 3" diameter mandrel hole was machined in each blank.

Each of the thus provided ring blanks were subjected to identical ring forging conditions wherein a reduction of 50 to was achieved with the following results:

Similar results have been achieved with rings having external diameters as large as 40 inches, internal diameters as large as 36 inches and a ring thickness as much as 10 inches.

Various modifications may be made in the process of the present invention without departing from the spirit or scope thereof and it is to be understood that I limit myself only as defined in the appended claim.

I claim:

The two step process for forming magnesium and magnesium base alloy 0 rings having isotropic physical properties which consists of a first step of providing an unworked cast ring blank defining an 0 and a second step of directly hot working said blank to increase both diameters of said blank.

References Cited by the Examiner UNITED STATES PATENTS 1,517,070 11/24 Jenkins 168 2,029,728 2/36 Lowry et a1. 2,064,323 12/36 Schmidt et a1. 29-5522 \VHITMORE A. WILTZ, Primary Examiner. HYLAND BIZOT, Examiner. 

